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Synthesis, crystallization and characterization of diastereomeric salts formed by ephedrine and malic acid in water

Wu, H; West, AR; Vickers, M; Apperley, DC; Jones, AG; (2012) Synthesis, crystallization and characterization of diastereomeric salts formed by ephedrine and malic acid in water. Chemical Engineering Science , 77 47 - 56. 10.1016/j.ces.2011.12.007. Green open access

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Abstract

A screening of crystallization conditions for the diastereomeric salts formed by L/D-malic acid and a common resolving agent, L-Ephedrine, in water is reported. So far, 7 different forms of salts with 1:1 and 2:1 stoichiometries were successfully crystallized, including one previously reported 1:1 LL salt. All new salts were characterized by differential scanning calorimetry, thermogravimetric and elemental analysis, infrared spectroscopy, solid-state NMR and powder XRD. 1:1 stoichiometry favours anhydrate formation while 2:1 stoichiometry tends to give monohydrate forms. Two monohydrates dehydrate on heating to produce anhydrous salts. A 2:1 LD trihydrate was discovered by vapor sorption experiments and is stable only at high relative humidity (>50%). Differences in stoichiometry and hydrate formation during salt crystallization, leading to differences in physicochemical properties could have a significant impact on resolution conditions and outcome.

Type: Article
Title: Synthesis, crystallization and characterization of diastereomeric salts formed by ephedrine and malic acid in water
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.ces.2011.12.007
Publisher version: http://dx.doi.org/10.1016/j.ces.2011.12.007
Language: English
Additional information: This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Keywords: Crystallization, Chiral separation, Ephedrine salts, Hydrates, X-ray diffraction
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: http://discovery.ucl.ac.uk/id/eprint/1339338
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